Exhausting and sealing method and apparatus



Nov. 11, 1941. l w. J. GEIGER ETAL EXHAUSTING AND SEALING METHOD AND APPARATUS Filed Oct. 7, 1938 Inventors Walter J. Gei

Wilson Davidson by Their Attorney.

Patented Nov. '11, 1941 EXHAUSTING AND SEALING METHOD AND APPARATUS WaIt er J. Geiger, Cleveland Heights, and Wilson Davidson, Cleveland. Ohio, allignon to General Electric Company, a corporation of New York Application October 7,1938, Serial No. 233,793

10 Claims.

Our invention relates to a method and apparatus for exhausting electric lamps and other sealed If the vessel is an incandescent lamp bulb having one of the particular metal and glass constructions shown in Patent No. 2,116,384, filed March 2, 1937, Paul O. Cartun, and Patent No. 2,191,346, filed April 30, 1937, A. Greiner, or a mercury :-switch of the type shown in Walker Patent 2,101,115, more than the usual difliculty and expense is experienced in attaching an exhaust tube thereto and there is a greater desirability for using the chamber type exhausting method. Such' metal and glass vessels are usually most easily exhausted through an aperture in the metal portion which is then closed by sealing a body of fusible material over the exhaust opening.

One of the objects of our invention-is to provide a satisfactory method and apparatus for sealing the exhaust opening in a vessel by melting a readily fusible material over said opening. Another object of our invention is to provide a method and apparatus for heating the fusible material from a source located outside of the exhaust chamber. A novel feature of our apparatusis the heating of the portion of the vessel adjacent its exhaust opening to melt the said fusible material by heat transferred from a highly heat-conductive 'portion of the container in contact therewith. Other features and advantages of our invention will be. apparent from the detailed description thereof which follows and from the accompanying drawing of species thereof.

In the drawing, Fig. l is a vertical section through apparatus comprising our invention with a double-ended electric lamp in place therein; Fig. 2 is a section through the apparatus oiFlg. 1 taken along the line 2-2; Fig. 3 is a vertical section through a modified form of apparatus; and Figs. 4 and 5 are similar vertical sections of other modifications illustrating the exhaustion of a mercury switch and a large type lamp respectivly.

The apparatus shown in Figs. 1 and-2 comprises an inverted bell housing It of minimum size to accommodate a sinsledouble-ended lamp I l of the type shown in the above-mentioned application of A. Greiner. The lamp ii is placed in thebell housing I. after removal of the cover 'plate I! which is then replaced inthe shownv and together with said bell housing ll completely encloses the lamp II in a sealed chamber. The lamp H has metal terminal thimbles or caps l3 and H at opposite ends which are sealed directly into the walls of the vitreous bulb l5 and is completely closed up except for the aperture I 6 in terminal thimble H. In position in the bell hoi'ising iii, the apertured thimble ll is located in the appendage or well member H in the highly heat-conductive bottom I8 thereof which conforms very closely to the shape of said thimble except for a groove or channel 18 extending down the sides and across the bottom thereof. The bottom portion iii of the chamber is preferably made of nichrome or other metal which may be silver soldered to the main portion of the chamber or container Ill. The groove I! in the bell housing bottom i8 forms a passage to aperture iii in the thimble H which permits the bulb l5 to be exhausted and gas filled at the same time as the interior of the bell housing ill. The

- may, for instance, be made from solder, a resin bottom ll of the bell housing iii in this instance is formed by aseparate thin piece of a corrosionresistant chrome-iron alloy brazed thereto. The lamp ii is provided with a bead or ring 20 of a glass or other fusible material suitable for sealing the aperture IS in the thimble H. The bead 20 rests/against the interior surface thereof but does not obstruct the flow of gas through said aperture i6.

Once the lamp H is properly located in the- -chamber formed by the bell. housing l0, said chamber and lamp i i are exhausted by means (not shown) connected thereto through pipe 2|. The lamp II and chamber are then preferably flushed with a gas and again exhausted before the exhausting operation is completed, whereupon heat is applied to the terminal thimble I4 and the bead 20 fused down over the aperture I. therein. The bead 20 is heated by means of the flame from burner 22 which is directed onto the outer surface of the well I! in the bell housing I. and quickly fuses said bead 20 because of the good conduction of the thin walls of the well H and the close contact of said well 11 and the thimble II. The bead 20 is preferably made of a vitreous material such as a low melting point glass and or other material which will seal the aperture satisfactorily upon cooling and which will have sufficient body whenmelted to close the aperture I6. The volume of the bead 20 should be such that it does not run out of the thimble l4 and into the well l'l. After a given heating period sufllcient to fuse the bead-2| and seal it to the thimble H, the flame is withdrawn from the well I! and the fused bead is allowed to cool whereupon the hold down screw 23 is turned back and the cover plate I! is removed and the lamp ll position so withdrawn. The cover plate I! is provided with.

since the arm :25 in which the screw 28 is threaded swings out of position. Since the bell housing l8 absorbs some heat from the fiame from burner 22 even though the conducting bodies are reduced to a minimum, additional 7 or member of the pipe 88. A closed chamber is means such as the block 28 are required to cool it. I The block '28 may, for instance, be a portion of an indexed turret carrying a plurality of the chambers l0 and may provide means for cooling the bell housing 18 by the flow of water.

The modification of our apparatus shown in Fig. 3 difiers from that just described only in the shape of the well I! which conforms completely to the shape of the terminal thimble i4 and has a tubular portion 21 extending therefrom by which the lamp H is exhausted. A-short length 28 of solder which has been inserted through the aperture IS in thethimble I4 is used in this case to seal the aperture l8 and, after the lamp II and chamber have been exhausted through the pipes 28 and 21, flames from burners 30 and}! are caused to play on the well I1 to melt said solder 28. This type well 11 allows any overflow of the sealing material to be withdrawn from the well "before it becomes sealed thereto. In Fig. 4 is shown a modification of our apparatus suitable for sealing a mercury switch 82 of the general type shown in Walker Patent 2,101,115 which issued December '7, 1937. The

switch 22 as shown is complete except for being exhausted and then gas filled through the openingflinthe conicalraisedbossflononeside thereof and the sealing of said opening 83 by the fusion of thevitreous material 85 already sealed to the boss 34. In our apparatus, the switch 32 is located within a chamber'formed by the bell housing 88 and the plate. 81. The boss 34 on said switch is located within an appendage member 88 of said chamber constituting an end of the pipe or conduit 8!). The plate 81 engages the bell housing 88 through the gasket 40 which seals the chamber and supports a spring 4| which engages and supports the switch 32. The

appendage 28 and'the outer portion of the boss 84 are both conical and the expanding force of the spring 4i pushes the switch 82 upward so that the boss 34 is forced into the appendage and makes reasonably good contact with the walls thereof.

Both the switch 32 and the chamber in which it is contained are in turn exhaustcdand then gas filled at the same time through pipes" and "42. Following these operations, the flames from burners 48 and 44 are directed onto the walls .of the appendage 88 and the heat conducted to the vitreous material 88 very quickly causes it to soften and flow over the openin 83 in saidcomprisesabulb 48,athreaded metalbaseshell 41 sealedthereto and a metal eyelet 48 secured to said shell 41 by a glass seal 48'. The lamp 4' is completely closed up except for the aperture 48 in the eyelet 48 which is frustro-conical 5 and fitssnugly in the tapered upper end by the use of sligh ly purerargon for the filling of material more readily fusible than the portion of, the vessel adjacent said opening, placing around the portion of the vessel adjacent its exhaust opening ll highly heat conductive member formed about the lamp 48 by the housing 8| and the cover plate 52 which are sealed by a gasket 83. The lamp is held down by a shoe which is pressed by a spring 84 the cover 82. The expanding force of the spring 54 forces the eyelet 48 into the conical end 88' of the pipe or conduit 88 which connects the lamp 45 to means (not shown) for exhausting and gas filling said lamp 45 in the manner desired. Since the eyelet 48 and the pipe 58 make only a-relatively weak seal therebetween, the chamber is exhausted and as filled at the same time as the lamp 48 by means connected thereto through pipe 56. In this particular instance, a plurality of loose pebbles or granules 51 ofla low melting point glass are located within the eyelet 48 and, when the gas filling is completed, the resistance coil 88 is-caused to heat these granules 51 until they are melted down over the aperture 48 in said eyelet 48. The resistance coil 58 is supported by the terminal posts 59 and 80 which are insulated from the housing 51 by the bushings 8|. The lamp. 48 is removed after suihcient time has elapsed to permit the fused mass formed by the granules 81 to cool.

The lamp 4! may be exhausted as follows: The chamber or container ii and lamp 48 are both evacuated, the chamber through conduit 86 and the lamp through conduit 58. The lamp is flushed through conduit 58 in the regular manner 1 with nitrogen, an adequate number of flushes being used to insure cleaning up the lamp. Since the chamber 5i has been evacuated, any leakage at the seal between the cap or eyelet 48 and the end' portion of conduit 58 will have no eflect on the lamp. The lamp is then filled with argon through conduit 50. While the lamp is being filled, nitrogen is supplied to the chamber .5! through conduit 56 at a rate which is regulated so that the pressure in the chamber is at all times approximately equal to the argon pressure in the lamp. Since the seal between eyelet 48 and conduit end 53' is fairly good and the pressure inside the lamp is roughly equal to the pressure outside of the lamp, any tendency for diffusion of nitrogen through the seal is slight and negligible contamination of the argon filling will result. "The gas loss is at a minimum because no argon escapes into the chamber. Any slight contamination of the argon may be compensated The lamp is then tipped'o'r sealed by w current throughheater 88 to melt the pebbles 81 and seal the exhaust opening 48.

Theuseofthistypeofexhausthasseveral advantages which cannot be derived from the type of equipment used at the present time. A broken lamp will have no eifect on the quality 'ofotherlampssinceeachlampisclosedoifin the chamber under vacuum. Moreover, the lamp rnaybenlledtoanydesireddegreeofpressure,

including p greatly above atmospheric, because there is no pressure diiferential between the lamp and the atmospheremrrolmding' it Whatweclaimasnewanddesiretosecureby:

Letters Patent of the United States is:

L'The method of evacuating a vase! having an exhaust opening therein which comprises placing adjacent said exhaust opening a quantity 1 through which the vessel may be exhausted, evacuating the vessel through said member and then'applying heat to said member from outside it to heat by conduction the portion of the vessel engaged thereby so as to fuse the said fusible material and seal the said exhaust opening without distorting the said portion of the vessel.

2. The method of evacuating a vessel having an exhaust opening therein which comprises placing adjacent said exhaust opening a quantity of material more readily fusible than the portion of the vessel adjacent said opening, placing around the portion of the vessel adjacent its exhaust opening a highly heat conductive member through which the vessel may be exhausted,

evacuating the vessel through said member and v a quantity of material more readily fusible than the portion of the vessel adjacent said opening, placing said vessel in a chamber, placing around and in fairly gas-tight contact with the portion of the vessel adjacent its exhaust opening a highly heat conductive end of a conduit, evacuating the vessel through said conduit and simultaneously evacuating said chamber, filling the vessel through said conduit with-a gas and simultaneously filling said chamber with a gas while maintaining the gaseous fillings in said vessel and chamber at substantially the same pressure, and then applying heat to the said end of the conduit from outside it to heat by conduction the portion of the vessel engaged thereby so as engaging conical portions of said conduit and.

vessel to render the joint therebetween substantially gas-tight, and means located externallyof and adjacent the said conical end portion of the conduit for heating it to conduit heat therefrom to the said conical metal portion of the vessel to fuse said fusible material to seal the said exhaust opening.

5. Apparatus for exhausting and sealing a vres-- sel having a metal thimble-shaped portion with an exhaust opening in the end thereof and' a" adjacent the said appendage for heating it to conduct heat therefrom to the said thimbleshaped portion of the vessel to fuse the fusible material.

6. Apparatus for exhausting and sealing a vessel having an exhaust opening therein with a readily fusible material disposed adjacent theretocomprising a highly heat conductive member shaped to engage and closely surround the portion of said vessel adjacent its exhaust opening, means associated with said member for connecting the vessel with a source of vacuum, and means located externally of and adjacent said member for heating it to conduct heat therefrom to the portion of the vessel engaged thereby to fuse said fusible material.

7. Apparatus for exhausting and sealing a vessel having an exhaust opening therein with a readily fusible material disposed adjacent thereto comprising a chamber for enclosing said vessel, a highly heat conductive member associated with said chamber and shaped to engage and closely surround the portion of said vessel adjacent its exhaust opening, means for connecting said chamber and vessel to evacuating means, and

means located externally of and adjacent said member for heating it to conduct heat therefrom to the portion of the vessel engaged thereby to fuse said fusible material.

8. Apparatus for exhausting and sealing a vessel having an exhaust opening therein with a readily fusiblematerial disposed adjacent thereto comprising a chamber for enclosing said vessel, a portion of a wall of said chamber being shaped to engage a substantial portion of said vessel adjacent the exhaust opening therein, means for connecting said chamber and vessel to evacuating means, and means located externally of said chamber and adjacent the said vessel-engaging portion of said chamber wall for heating it to conduct heat therefrom to the portion of the vessel engaged thereby to fuse said fusible material.

9. Apparatus for exhausting and sealing a vessel having an exhaust opening therein with a readily fusible material disposed adjacent thereto comprising a chamber for enclosing said vessel, a portion of a wall of said vessel being shaped to engage a substantial portion of said vessel adjacent its exhaust opening with the interior of saidvessel in communication with said chamber through said exhaust opening, means for connecting said chamber to a source of vacuum, and means located externally of said chamber and adjacent the said vessel-engaging portion of said chamber wall for heating it to conduct heat therefrom to the portion of the vessel engaged thereby to fuse said fusible material.

10. The method of evacuating a vessel having an exhaust opening therein which comprises placing adjacent said exhaust opening a quantity of material more readily fusible than'the portion of the vessel adjacent said opening, placing said vessel in a chamber with the said portion thereof engaging a substantial part of a highly heat conductive portion of said chamber, evacuating the said chamber and vessel, and then applying heat from the exterior of the chamber to the said heat conductive portion ofsaid chamber to heat by conduction the portion of--the vessel engaged thereby so as to fuse the said fusible material and seal the exhaust opening without distorting the said portion of the vessel.

WALTER J. omega. wn sou DAVIDSON. 

